1. Field of the Invention
The present invention relates to an object levitating apparatus and its process, which levitates an object in the air (the term xe2x80x9clevitatexe2x80x9d here refers to the action of lifting an object so as to be in a floating state), and an object transporting apparatus equipped with said apparatus.
2. Description of the Prior Art
The following systems are known in the prior art as examples of this type of apparatus.
(1) A system wherein an object is magnetically levitated and transported using an alternating current magnetic field flowing through a coil;
(2) A system wherein an object is levitated and transported using the Meissner effect of superconductivity; and,
(3) A system wherein an object is levitated and transported using pressurized air such as compressed air.
In the apparatuses described in (1) and (2) above, together with the object to be levitated and transported being limited to a ferromagnetic substance or semiconductor, these apparatuses also have the disadvantage of being unable to be applied to objects for which the placing under conditions of being subjected to magnetism is undesirable. In addition, with respect to the apparatus above which uses the Meissner effect of superconductivity, since an expensive coolant is required to cool a coil to an extremely low temperature, together with this leading to increased costs with respect to the consumption of this coolant, considerations also must be taken with respect to the safety of the coolant. Moreover, this apparatus also has the disadvantage of having to be made extremely large in order to levitate and transport objects for an extended period of time in a stable state.
On the other hand, in the apparatus described in (3) above, since a pressurized gas is required to be supplied to the entire surface of the object transport path, together with having to provide an elaborate pressurized gas supply device which thereby makes it difficult to reduce the size of the entire apparatus, this apparatus also suffers the disadvantage of encountering difficulty in controlling the pressure of the supplied gas so that it remains uniform over a wide range. In addition, in the case of using said apparatus under conditions in which the atmosphere must be kept clean, such as in a so-called xe2x80x9cclean roomxe2x80x9d, a device is required for suctioning and recovering any gas that escapes from the above-mentioned pressurized gas supply device to prevent diffusion of said escaped gas. In addition to this being an additional obstacle to reducing the size of the apparatus, this apparatus also has the disadvantage of it being difficult to completely recover the gas.
However, an apparatus like that shown in FIG. 1 has recently been developed. Furthermore, this apparatus is disclosed on pages 745 and 746 of the xe2x80x9cLecture Collection of the Japan Acoustics Societyxe2x80x9d published on Oct. 3, 1983.
Namely, in FIG. 1, a standing wave (not shown) is produced between stepped circular diaphragm 2, vibrated by vibrating device 1, and correspondingly arranged reflecting plate 3, and a plurality of Styrofoam spheres 4 (weight: 1.2 mg, diameter: 4 mm) are levitated by a sound field. Furthermore, in FIG. 1, the direction of gravitational force is shown with arrow g. In this case, it has been verified that each of the spheres 4 is stationary in the air at an interval of xc2xd the wavelength of the ultrasonic waves, and their positions are at the valleys of sound pressure. In addition, the size of spheres able to levitated is no more than xc2xd the wavelength, and their weight is considered to be related to sound pressure.
However, in this type of apparatus of a constitution which uses a standing wave to make an object become stationary in the air at the locations of its nodes, the sphere 4 used for the testpiece is currently limited to that which is extremely lightweight, and the vibration amplitude of diaphragm 2 must be made extremely large in order to levitate heavier and larger objects. Thus, in consideration of the stress-related destruction of diaphragm 2 and horn 1a (see FIG. 1), it would be difficult for this apparatus to stably levitate a heavy object for an extended period of time, thus making practical application of this apparatus far from attainable. In addition, although the use of a process in this constitution whereby sound waves are converged into powerful sound waves to allow levitation of relatively heavy objects can be considered, since sound waves would act on a small surface area in comparison with the diameter of diaphragm 2, the result would still be that the apparatus would still only be applicable to small objects.
In consideration of the above-mentioned disadvantages of the prior art, the object of the present invention is to provide an object levitating apparatus, an object transporting apparatus equipped with said object levitating apparatus as well as an object levitating process and object transporting process, which together with not placing restrictions on the material and so forth of the objects handled, is able to handle objects having relatively large weights and dimensions, while also being compact in size, inexpensive, preferable in terms of safety and so forth, and easy to control.
The present invention composes an object levitating apparatus, equipped with a vibrator and an ultrasonic excitation device that excites said vibrator, which levitates an object above the surface of said vibrator by the radiation pressure of sound waves of said vibrator; wherein, said entire vibrator vibrates longitudinally roughly perpendicular to said surface.
In addition, the present invention composes an object levitating apparatus, equipped with a vibrator and an ultrasonic excitation device that excites said vibrator, which levitates and causes an object to travel above the surface of said vibrator by the radiation pressure of sound waves of said vibrator; wherein, said entire vibrator vibrates longitudinally roughly perpendicular to said surface.
In addition, the object levitating process according to the present invention produces longitudinal vibrations in a vibrator that are roughly perpendicular to its surface, and levitates an object above said surface by the radiation pressure of sound waves of said vibrator.
Moreover, the present invention composes an object levitating apparatus, equipped with a vibrator and an ultrasonic excitation device that excites said vibrator, which levitates an object above the surface of said vibrator by the radiation pressure of sound waves of said vibrator; wherein, said ultrasonic excitation device excites said vibrator so as to vibrate in a slit vibration mode.
In addition, the present invention composes an object levitating apparatus, equipped with a vibrator and ultrasonic excitation device that excites said vibrator, which levitates and causes an object to travel above the surface of said vibrator by the radiation pressure of sound waves of said vibrator; wherein, said ultrasonic excitation device excites said vibrator so as to vibrate in a slit vibration mode.
In addition, the object levitating process according to the present invention produces slit mode vibrations in a vibrator, and levitates an object above said surface by the radiation pressure of sound waves of said vibrator.